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Fractionated extracts of persimmon (Diospyros kaki) peels were studied for cytotoxic activity, multidrug resistance (MDR) reversal activity, anti-human immunodeficiency virus (HIV) activity and anti-Helicobacter pylori (H. pylori) activity. The potent cytotoxic activity against human oral squamous cell carcinoma cells (HSC-2) and human submandibular gland tumor (HSG) cells was found in the acetone fractions (A4 and A5) with IC(50) ranging from 21 to 59 micro g/mL. However, the cytotoxic activity was not correlated with the radical intensity of the fractions. Three 70% MeOH extract fractions (70M2-4) produced radical and efficiently scavenged the O(2)(-) produced by hypoxanthine and xanthine oxidase reaction. All of the fractions tested were not effective for anti-H. pylori and anti-HIV. Fractions H3 and H4 of hexane extract, and M2 and M3 of MeOH extract showed a remarkable MDR reversal activity comparable with that of (+/-)-verapamil (a positive control). These results indicate the therapeutic value of persimmon peel extracts as potential antitumor and MDR-reversing agents.

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Phenothiazines, a kind of sulfur-containing tricyclic compounds, have diverse biological activities including tranquilizer, antibacterial, antitumor and antihelmintic activities due to the relatively lower cytotoxicity. Phenothiazines have been used for clinical treatments as psychotropics. In contrast to the psychotropic preparations, their information of other biological activities of phenothiazines and their related compounds has been limited. This review article summarizes the interaction with DNA (using quantum calculation), antitumor activity, differentiation or apoptosis-inducing activity, tumor necrosis factor (TNF)-induction, antiproliferative activity, radical scavenging activity, antimutagenic activity, antiplasmid activity, antibacterial activity, reversal of multidrug resistance (MDR), blast transformation activity of phenothiazines, benz[c]acridines and benzo[a]phenothiazines.

The antibacterial activity and influence on lipid model membranes and erythrocyte membranes of 24 N-acylphenothiazines and trifluoperazine were studied. (1) Among 24 phenothiazines, the antimicrobial activity of amino maleates was the highest. (2) The influence of phenothiazines on model liposome and erythrocyte membranes was studied using N-phenyl-1-naphthylamine (NPN) as fluorescence probe. From the three types of phenothiazine substitution (H, Cl, CF3) at position 2, CF3-phenothiazines were the most effective in the interaction with liposomal membranes. (3) As measured by the polarization degree of 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence, the alteration of membrane fluidity induced by CF3-phenothiazines was the biggest. Surprisingly, phenothiazines induced stomatocytic shape alterations (invaginations) in erythrocytes and at higher concentrations, also hemolysis of erythrocytes was observed. (4) The microcalorimetic measurements of influence of phenothiazines on thermal behaviour of synthetic lipid systems confirmed the previously obtained results. The main transition temperature and enthalpy of transition of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) were significantly modified by CF3-phenothiazines, suggesting their penetration of the lipid bilayer. Above results show that phenothiazine maleates were generally more effective than other phenothiazines used in this study.